From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.4 required=3.0 tests=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,USER_IN_DEF_DKIM_WL autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 015ECC433E0 for ; Mon, 8 Jun 2020 14:51:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C3383206C3 for ; Mon, 8 Jun 2020 14:51:53 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="H0W6Kxn1" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730077AbgFHOvx (ORCPT ); Mon, 8 Jun 2020 10:51:53 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45802 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725975AbgFHOvw (ORCPT ); Mon, 8 Jun 2020 10:51:52 -0400 Received: from mail-wr1-x441.google.com (mail-wr1-x441.google.com [IPv6:2a00:1450:4864:20::441]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 40099C08C5C2 for ; Mon, 8 Jun 2020 07:51:52 -0700 (PDT) Received: by mail-wr1-x441.google.com with SMTP id l10so17705867wrr.10 for ; Mon, 08 Jun 2020 07:51:52 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=09t4vJAEJNOcAKbjc/XrD7rKiwG3r51o8wQyvTLcyH8=; b=H0W6Kxn1tWB0Gd5mhqe5+76N1JoRrfQBzuFyeHyKdKuKr3c0mxvi1yAFcfLLIJyh55 0k8dOPOj9CmK+GRAegeskyYIv+TKDj2iQeUXFmB0nzECSIxyFfzhVJWU9aWVBdTEchFP GlzcpS27DdL03xE79FQZzpNvHLcxsYPNwzcAPR76BqA9jTXdUk/YUdxlqW4FAdbBRwNf larkyRCJnjdssMA6KHO2gAUNviKrbJ7XhB3sWo/Wp1musUseGP2k62qvdmy2yuoLieci tP3J5viTXpUZQyvmoWug1BfYa6vn0NDeWQAQ07YD0Y4SXO0NCVrrvhcExX8dj7+yQfL9 PSSA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=09t4vJAEJNOcAKbjc/XrD7rKiwG3r51o8wQyvTLcyH8=; b=U1EQuXueewYuPlk83+kKtb49g4SBGtIdABChOd6MP/AQWkgqLBDcy4V/feZG8lZwPN NgWLDJLA/rGD9SCy5mKk1vZ78NWQNnBU9nbYpY+lkRGlIeSqmjJp0rAViCODD9TVN36p YDEmqziNDYcfUltaaO5YU+kA6b7Y9QbLB0CXUiUSh1HcIi4RcX6LdRF96fXIjIXAZLYm FaFkU76eTFMvRqOV1AzSTHQhXaFj8JsF8eyJWQGOQZqJvb9bGIxzD6XUjJFmC1pqbnVS Y3coTHx50A0ftluLOj4nga+edH1IFEgsDbBDRwPyse9p6HB/y3tsjC/6we2fz5gYvMmO 4w0g== X-Gm-Message-State: AOAM531+eqYSSu7xuLWI0aqm2xRS+tGa7h77FAyy+Ltg/9wCt2HDqXD1 f3pCxjkvVziskdLkp7H4yvCEpA== X-Google-Smtp-Source: ABdhPJw/eKBztQ3a9E6WKUS5WsHzaQqYg5KTtA62h7WxrR2Vb+QDhRKkaSCaXQP78CvwMVocDYT20A== X-Received: by 2002:a5d:558a:: with SMTP id i10mr25577401wrv.207.1591627910886; Mon, 08 Jun 2020 07:51:50 -0700 (PDT) Received: from google.com ([2a00:79e0:d:109:355c:447d:ad3d:ac5c]) by smtp.gmail.com with ESMTPSA id c5sm19131623wma.20.2020.06.08.07.51.49 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 08 Jun 2020 07:51:50 -0700 (PDT) Date: Mon, 8 Jun 2020 15:51:45 +0100 From: Andrew Scull To: Marc Zyngier Cc: kvm@vger.kernel.org, kvmarm@lists.cs.columbia.edu, linux-arm-kernel@lists.infradead.org, James Morse , Julien Thierry , Suzuki K Poulose , Mark Rutland , kernel-team@android.com Subject: Re: [PATCH v2] KVM: arm64: Remove host_cpu_context member from vcpu structure Message-ID: <20200608145145.GA96714@google.com> References: <20200608085657.1405730-1-maz@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200608085657.1405730-1-maz@kernel.org> Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Mon, Jun 08, 2020 at 09:56:57AM +0100, Marc Zyngier wrote: > For very long, we have kept this pointer back to the per-cpu > host state, despite having working per-cpu accessors at EL2 > for some time now. > > Recent investigations have shown that this pointer is easy > to abuse in preemptible context, which is a sure sign that > it would better be gone. Not to mention that a per-cpu > pointer is faster to access at all times. Helps to make the references to `kvm_host_data` clearer with there now being just one way to get to it and shows that it is scoped to the current CPU. A good change IMO!